The goal of this proposal is to overcome the limitations of current gene therapy technologies by developing a viable vector platform for selective gene delivery to dopaminergic (DA) neurons, as a means of treating Parkinson disease (PD). To develop the vector platform and validate its effectiveness, our aims are threefold: 1) develop an adenoviral vector (Ad) that targets DA neurons of the substantia nigra, 2) Employ this vector to deliver neuroprotective factors, and 3) validate its efficacy as a neuroprotective strategy in the murine MPTP model of PD. To accomplish Aim 1, tropism modified Ads will be assessed in vitro and in vivo for affinity to DA neurons. To determine this tropism, immunohistochemical analysis will be utilized. Combining the properties of the best targeting vectors, mosaic technology will be used to incorporate multiple targeting molecules in a single vector. Finally, inclusion of a restrictive promoter will further confine expression of delivered genetic material. At each step, immunohistochemistry will assess localization and laser capture microdissection followed by quantitative rtPCR will assess expression of the transgene in the cells of interest. In order to assess the efficacy of this vector as a platform for therapy, the reporter transgene will be replaced with GDNF. We will then validate the vector's ability to deliver this therapeutic payload to a high proportion of the SN while maintaining appropriate levels of transgene expression in those cells by assessing GDNF immunohistochemistry, along with GDNF ELISA, TH enzyme activity and protein level, and DA quantitation. To assess the neuroprotective potential of this vector, a pretreatment paradigm delivering GDNF prior to MPTP intoxication will be utilized. Brain tissue will be analyzed for DA content and nigral sections will be assessed by unbiased stereology to evaluate the neuroprotective potential of this vector. The culmination of these studies will result in the development of a DA-targeted vector platform featuring the ability to deliver novel therapeutics to degenerating neurons of the substantia nigra. RELEVANCE TO PUBLIC HEALTH: Currently, advanced therapeutic strategies for treatment and modulation of the PD process exist, but their utility is hindered by an inability to deliver them in a robust, targeted manner. The availability of a delivery platform that can accommodate current and future treatment strategies will speed the translation of novel therapies from the laboratory to the clinical bedside.